I've exported my svg image to PNG with dpi=300 in Inkscape. Image size was :1860x1080 px
I've also converted the same svg image with some python script to PNG with dpi also set to 300. The size was the same - 1860x1080 px

Next I've included both PNG images to MS word 2003 document, then I've printed it into PDF (as I usually do before real print). I've done a screenchot of this PDF page. And see what I've got:

The bottom image is from Inkscape - it looks awful and ugly. Why???? Both images are identical in my monitor but printed version shows the difference!!

Why I can't see my image?
Image url: http://bayimg.com/fApNCaAbi

inkoqnito wrote:Why I can't see my image?

It's because you're linking to a webpage, not the image.

inkoqnito wrote:The bottom image is from Inkscape - it looks awful and ugly. Why?

It could be because the PNG uses alpha transparency. In Inkscape, in your document properties, change the document background colour to be solid white with no transparency then save the image as PNG.